This pair of Matsushita 6CA7 had made it all the way through sound check, and we were about to begin before the amplifier cut out and started stinking up the place.
Carbon path through this former screen grid resistor now sits at ~60 ohms.
Showing posts with label resistance. Show all posts
Showing posts with label resistance. Show all posts
Friday, June 13, 2014
Monday, March 14, 2011
Spent a few hours yesterday without electricity, always a nice reminder of paper books, ink and fire. Don't lose sight of that stuff my friends.
So hindered by the absence of a search function I wound up lackadaisically perusing my paper copy of the Mouser catalog, which led me to this image:
Naturally, I'm led to believe that their superior resistor product is illustrated on the left.
It's the image on the right that tickles my fancy, however.
I've been plucking the used/clogged activated charcoal water filters from the trash (if they make it that far) in order to secure carbon materials with which to roll my own hopelessly noisy carbon resistors. The material itself is doubtless contaminated with all manner of miscellaneous bullshit that wouldn't make it past the door of any self respecting factory with the pressing goal for rampant pasteurization. I also highly doubt the resulting resistors will be RoHS compliant.
After rolling the material out I let it dry a few days. It does indeed reflect a resistance. Actual assembly is yet to be determined; I'm thinking Pyrex tubing cut to length, conductive plug/leg cemented in one end, infill of material gently compressed, over which another conductive plug/leg will be cemented.
Values will be arrived at through trial and error.
I was planning on posting about this project once I had made a few and could outline the process, but that catalog image forced my hand.. their rendition of the poor substrate is strikingly similar to my material of choice.
So hindered by the absence of a search function I wound up lackadaisically perusing my paper copy of the Mouser catalog, which led me to this image:
Naturally, I'm led to believe that their superior resistor product is illustrated on the left.
It's the image on the right that tickles my fancy, however.
I've been plucking the used/clogged activated charcoal water filters from the trash (if they make it that far) in order to secure carbon materials with which to roll my own hopelessly noisy carbon resistors. The material itself is doubtless contaminated with all manner of miscellaneous bullshit that wouldn't make it past the door of any self respecting factory with the pressing goal for rampant pasteurization. I also highly doubt the resulting resistors will be RoHS compliant.
After rolling the material out I let it dry a few days. It does indeed reflect a resistance. Actual assembly is yet to be determined; I'm thinking Pyrex tubing cut to length, conductive plug/leg cemented in one end, infill of material gently compressed, over which another conductive plug/leg will be cemented.
Values will be arrived at through trial and error.
I was planning on posting about this project once I had made a few and could outline the process, but that catalog image forced my hand.. their rendition of the poor substrate is strikingly similar to my material of choice.
Friday, December 31, 2010
The dryer is my auxiliary work bench.
Burning in the recapped Princeton with the variable AC/DC power supply I spoke of a while back.
I'm excited about the ammeter on the front panel, makes me wish this unit was good for more than 1-2.25 amps (doubt I'll push it beyond the range of the panel meter). The only modification I exercised on the unit was removal of the 10 watt 150 ohm resistor strapping the DC output jacks. It would heat up CONSIDERABLY at a fraction of the range I will be using.
As far as I can tell, the reason it was there in the first place was to drain off stored charge in the capacitors, as they don't have resistors to drain voltage when powered off. I'd rather install a high value resistor across the cap itself as opposed to keeping the low value space heater hanging off the front panel.
My plan for the immediate future is to process a few unknown amps and form up a component shopping list to exact repairs.
Burning in the recapped Princeton with the variable AC/DC power supply I spoke of a while back.
I'm excited about the ammeter on the front panel, makes me wish this unit was good for more than 1-2.25 amps (doubt I'll push it beyond the range of the panel meter). The only modification I exercised on the unit was removal of the 10 watt 150 ohm resistor strapping the DC output jacks. It would heat up CONSIDERABLY at a fraction of the range I will be using.
As far as I can tell, the reason it was there in the first place was to drain off stored charge in the capacitors, as they don't have resistors to drain voltage when powered off. I'd rather install a high value resistor across the cap itself as opposed to keeping the low value space heater hanging off the front panel.
My plan for the immediate future is to process a few unknown amps and form up a component shopping list to exact repairs.
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